This invention relates to a tubing coupler that has primary and secondary sealing devices. The coupler is designed such that if the primary sealing device fails the secondary sealing device will prevent the travel of fluid between the interior of the system and the outside atmosphere. The coupler is further designed such that, if necessary, it can be assembled without the secondary sealing device and function properly, provided the primary sealing device does not fail. The coupler can also be disassembled and subsequently reassembled with the original primary and secondary sealing devices.